This application is a U.S. National Phase Application Under 35 USC 371 of International Application PCT/IL00/00716 (published in English) filed Nov. 5, 2000.
The present invention relates to tree-shaking harvesting equipment, and in particular to the vibration generation unit which actuates such equipment.
Traditionally, picking fruit and nuts from trees was always done manually and was inherently labor intensive. With the rise of wages and the increase of competition in the food supply market, efforts were made to mechanize the harvesting of trees and to provide for methods that are more efficient. Because of this quest, tree-shaking machines were developed. Those tree shakers are equipped with a pair of two opposing clamps, which firmly engage a tree on two diametrical sides of the trunk. The tree shaker also comprises a vibration generation unit that is connected to the clamps of the tree-shaking machine. Once the clamps are engaged, the tree is shaken to remove the fruit, with the intent that the inertial forces that will develop on the fruit will exceed the bonding force between the fruit and the stem.
A vibration generation unit is typically driven by a dual oscillation mechanism, which operate substantially independently of one another. An example is provided in U.S. Pat. No. 3,338,040 which shakes the tree in a number of different random directions. Such action is undesirable, because some of these directions may cause damage to the tree. For example, those directions in which the clamps vibrate tangentially to the trunk cause transverse shear which can strip tree bark and abrade the stem. Furthermore, two randomly vibration generation units do sometimes oppose one another and cause energy dissipation; or excessively reinforce one another and thereby exert exaggerated compressive forces on the tree.
Efforts to coordinate the action of the two vibration generating units, such as modification of the moment of inertia of the spinning rotators resulted in U.S. Pat. Nos. 3,548,578 and 4,903,471. But even those improved devices wrench the trees across a range of directions at once, risking damage to the root system. Experiments were also conducted with the variation of the frequency of shaking, to reach the natural resonance frequency of the tree. It was thought that if it would be possible to reach the maximum amplitude of displacement, then the most efficient tree harvesting conditions would be s obtained. A limb shaker having a variable throttle arrangement that can be adjusted until the greatest displacement is observed is taught in U.S. Pat. No. 3,650,099. However, with a manual throttle setting device, the shaker was poorly suited for commercial harvesting.
In a paper of the American Society of Agricultural Engineers, by J. D. Whitney, G. H. Smerage and W. A. Block, No. 0001-2351/90/3304-1066, published in April 1990, there is mention of a shaking system with a three-shaft linear vibrator. As shown in FIG. 1, the elements of the system comprise a vibration unit A, a tree clamp C engaging a trunk B and part of the shaker machine D. The vibration unit A consists of three identical vertical sprocket wheels mounted side by side on a horizontal frame beam F inside a housing H. One sprocket wheel MS, the middle one for example, is driven by a motor M, not shown in FIG. 1 for the sake of clarity, and the other two sprocket wheels, on the sides of the driven sprocket wheel MS, are driven sprockets S. A chain CH couples the three sprocket wheels, with the slack side SS of the chain CH, running substantially in parallel and below the frame beam F. The slack side SS is tensioned by an idler ID. The two driven sprocket wheels S are engaged by the chain CH to rotate in the same direction while the middle driving sprocket MS counter-rotates. This is achieved by running the chain over both side sprocket wheels S but under the driven sprocket wheel MS.
To generate vibrations, the sprocket wheels carry eccentric weights. A single weight G is mounted eccentrically on each one of the sprocket wheels S while a double weight 2G is mounted with the same eccentricity on the driven sprocket wheel MS. With reference to FIG. 1, the single weights G and the double weight 2G are all aligned to the east, according to the directions of the compass card. A force vector equal to the sum of forces applied by the two single weights G and the one double weight 2G is thus applied eastwards.
Assuming that the driven sprocket wheel MS rotates anti-clockwise, then both sprocket wheels S will rotate clockwise. FIG. 2 now represents the s vibration unit A after a quarter of a turn of the sprocket wheels, according to the assumed direction of rotation. The single weights G on the sprocket wheels S now point northwards while the double weight 2G points southwards. The force vector of the sum of forces applied all the weights, namely, two single forces G pointing to the north and one double weight 2G directed to the south, now equals zero, and thereby, the upward and the downward forces cancel out.
Another quarter of turn of the sprocket wheels is depicted in FIG. 3. This time all the weights are aligned westwards. The resultant force vector is thus the same as at the start, as shown in FIG. 1, but in the opposite direction. One more quarter of a turn, not illustrated in a drawing, would result in a rotation of 180 degrees of all the sprocket wheels relative to FIG. 2, whereby the force vector would again sum up to zero. It has thus been shown that the vibration unit A is a linear shaker: theoretically, forces appear only horizontally, in the east to west direction, while no forces are generated vertically, north-south.
In practice however, the results are quite different. First, the vibration unit A is limited to rather slow rotational velocities, due to the chain drive, which makes it unfit for the harvesting of smaller fruit. Second, the vibration unit A develops severe wear and tear, resulting in costly maintenance expenses. Third, the vibration unit A engages the tree trunks with its longitudinal axis in the direction of shaking, thus rendering it very awkward to operate.
Although tree shakers are readily available, their vibration generating units still suffer from various drawbacks such as slippage, loss of rotational synchronization which causes deviation from a single shaking direction, as well as damage to tree trunks and overall low harvesting efficiency.
For the above-mentioned reasons, there is obviously a need for better vibration generating units that keep their synchronization, are cheap to maintain and operate, and are easy to use. Moreover, there is definitely a need for equipment which features high efficiency harvesting and is inexpensive to manufacture.
It is an object of the present invention to provide a vibration generation mechanism for the high efficiency harvesting of trees.
It is another object of the present invention to provide a vibration generation mechanism, which is simple to use and operate.
It is a further object of the present invention to provide a vibration generation mechanism that will not harm the trees during shaking.
It is yet another object of the present invention to provide a unitary improved but simple vibration generation mechanism featuring low costs of production, of operation and of maintenance.
Still another object of the present invention is to provide a vibration generation mechanism, which is reliable and long lasting.
It is an object of the present invention to provide a linear vibration generation mechanism for a tree trunk shaker, the shaker comprising a pair of clamps for locking on the trunk on opposite sides thereof and the linear vibration generation mechanism comprising:
at least one motor for providing rotational motion at a predetermined angular velocity,
a transmission coupled to the at least one motor, the transmission for providing a counter-rotating motion,
a pair of identical eccentric rotators coupled to the provided counter-rotating motion, the pair of eccentric rotators rotating in parallel planes and at same angular velocity, and
an enclosure for containing the linear vibration generation mechanism, the enclosure being associated with one clamp of the pair of clamps. The enclosure is possibly an integral part of one clamp of the pair of clamps.
It is another object of the present invention to provide a linear vibration mechanism, where the pair of eccentric rotators further comprises:
at least one weight, and
an arm having for releasably but fixedly supporting the at least one weight in adjustable position thereon, and the arm accommodates for the support of different at least one weight(s) and allows adjustment of the at least one weight(s) to achieve different identical eccentricity of the pair of eccentric rotators.
Another object of the present invention is to provide a way to define the direction of linear vibration by alignment of the at least one weight of each one of the pair of eccentric rotators in the desired direction of vibration.
Yet another object of the present invention is to allow a choice of motor from hydraulic motors, electric motors, internal combustion motors and pneumatic motors, or the selection of a motor built as a hydraulic motor of the gear-on-gear type, either with spur gears or with helical gears. It is also possible to have the at least one motor also serves as the transmission for providing counter-rotating motion. Evidently, the predetermined angular velocity of the motor is controllable.
Moreover, another object of the present invention is to provide a linear vibration mechanism wherein the at least one hydraulic motor comprises a modification of a conventional gear-on-gear oil pump into a hydraulic motor, wherein
the conventional gear-on-gear oil pump comprises:
a housing having a first side in parallel and opposite to a second side, the housing also comprising a third side opposite to a fourth side, the first side being perpendicular to the third side, the housing being sealed close, and the housing defining an inside and an outside,
a first drive gear,
a driven gear of the same size as the first drive gear, the first drive gear and the driven gear meshing side-by-side in counter-rotation inside the housing,
a first driving shaft coextensive and coaxial with the first drive gear, the first driving shaft protruding outside of the first side of the housing in sealed engagement therewith,
an oil inlet port located amid the third side, and
an oil outlet port located amid the fourth side, and
the at least one hydraulic motor comprises:
the conventional gear-on-gear oil pump,
a second drive gear,
a second driving shaft, the second driving shaft and the second drive gear being of the same size as the first drive gear and the first driving shaft, the second drive gear meshing with the first drive gear in replacement of the driven gear, and the second driving shaft protruding outside of the second side of the housing in sealed engagement therewith, the first driving shaft and the second driving shaft being parallel to each other,
whereby supply of oil under pressure to the oil inlet port counter-rotates the first drive gear in mesh with the second drive gear to counter-rotate the first driving shaft and the second driving shaft and thereby creating a hydraulic motor which also serves as the transmission for providing counter-rotating motion. The gears of the first drive gear and of the second drive gear are selected from the group consisting of spur gears and helical gears.
Furthermore, it is another object of the present invention to provide a vibration generation mechanism where the at least one motor further comprises:
an output shaft, and
the transmission further comprises:
a housing comprising a first side and a second side, the second side being opposite to and in parallel with the first side, the housing defining an inside and an outside, the first side outside supporting the at least one motor with the output shalt thereof entering inside the housing through the first side and protruding outside of the second side,
a first gear coupled to the output shaft inside the housing,
a second gear of the same size as the first gear, the second gear and the first gear meshing side-by-side in counter-rotation inside the housing, and
a driven shaft coextensive and coaxial with the second gear, the driven shaft exiting the housing and protruding outside the first side of the housing, and the output shaft being parallel to the driven shaft,
the housing further accommodating bearings to support the output shaft, the first gear, the second gear and the driven shaft,
whereby rotation of the at least one motor counter-rotates the output shaft relative to the driven shaft. The housing may be selected from the group consisting of an open housing, a closed housing and a sealed housing.
In addition, it is another object of the present invention to provide a vibration generation mechanism where the at least one motor further comprises:
a first motor having a first output shaft and a second motor having a second output shaft, the first motor rotating in direction opposite to rotation direction of the second motor, and
the housing further comprising:
the first side outside supporting the first motor and the second side outside supporting the second motor,
the first output shaft and the second output shaft penetrating from the side of their respective motor to inside the housing and protruding to the opposite side outside, the first output shaft and the second output shaft being parallel, and
the first gear and the second gear being coupled, respectively, to the first output shaft and to the second output shaft. In this case, the first gear and the second gear synchronize rotation of the first motor and of the second motor.
It is another object of the present invention to provide that the at least one motor further comprises an output shaft, and the transmission comprises:
a housing of rectangular cross-section having a first side, a second side, a third side and a fourth side, the first side and the third side being opposite to and in parallel with, respectively, the second side and the fourth side, the sides of the housing defining a housing inside and a housing outside, with the first side outside supporting the at least one motor with the output shaft thereof penetrating inside the housing,
a drive pinion coupled to the output shaft inside the housing, the drive pinion being a rotatably mounted bevel gear,
a pair of coaxial parallel bevel gears meshing in perpendicular with the drive pinion, each one of the pair of bevel gears being rotatably located inside the housing, respectively on the third side and on the fourth side,
a pair of coaxial driven shafts protruding outside the housing, each one of the pair of driven shafts being coupled to each one of the pair of parallel bevel gears, the output shaft and the pair of driven shafts residing in the same plane,
whereby rotation of the output shaft drives the parallel bevel gears in counter-rotation, thereby counter-rotating the pair of driven shafts. The housing is selected from the group consisting of an open housing, a closed housing and a seated housing.
Still another object of the present invention is to provide a vibration generation mechanism where the at least one motor further comprises:
a first motor having a first output shaft and a second motor having a second output shaft, the first motor rotating in direction opposite to rotation direction of the second motor,
the housing further comprising:
the first side outside supporting the first motor and the second side outside supporting the second motor,
the first output shaft and the second output shaft penetrating from the side of their respective motor to inside the housing,
a first drive pinion and a second drive pinion located inside the housing and coupled respectively, to the first output shaft and to the second output shaft, the first drive pinion and the second drive pinion being a rotatably mounted bevel gear,
a pair of coaxial parallel bevel gears meshing in perpendicular with the first drive pinion and a second drive pinion, each one of the pair of bevel gears being rotatably located inside the housing, respectively on the third side and on the fourth side,
a pair of coaxial driven shafts protruding outside the housing, each one of the pair of driven shafts being coupled to each one of the pair of parallel bevel gears, the first output shaft and the second output shaft and the pair of driven shafts residing in the same plane,
whereby rotation of the output shaft drives the parallel bevel gears in counter-rotation, thereby counter-rotating the pair of driven shafts. In this case also, the first drive pinion and a second drive pinion and the pair of coaxial parallel bevel gears synchronize the rotation of the first motor and of the second motor.